Hello, I’m helping a friend install one of my old hds 7 T at the dash on his boat. It currently has an hds 5 flush mounted…will the dhs 7 fit if cut the larger hole? I am not familiar with flush mounts, I had one on an old 520c and it had a bracket that held it in there, I assume that is how I will need to do the new one as well? Can I buy the flush mount kit that has said bracket? Thanks in advance